Chapter 3: Periodic Table and Elements

Flashcards covering key vocabulary, concepts, theories, and historical discoveries related to the periodic table, elements, atoms, and subatomic particles, as presented in the lecture notes.

Elements

A type of pure substance, considered the building blocks of everything, composed of about 100 basic substances. There are currently 118 elements discovered and isolated.

Synthetic Elements

Man-made elements created in a lab, often radioactive, unstable, and having a high degree of reactivity.

Pure Substance (Elements)

The simplest type of pure substance that cannot be broken down any further, serving as the building blocks and backbones of all substances and matter.

Compounds

Formed by combining two or more elements; they are pure substances that can be broken into their respective elements using chemical means.

Chemical Symbols

Unique one or two-letter abbreviations for each element on the periodic table, with the first letter capitalized and the second (if present) lowercase.

Gold (Au)

An element whose symbol 'Au' is derived from its Greek name 'aurum'.

Lead (Pb)

An element whose symbol 'Pb' is derived from its Latin name 'plumbum'.

Tungsten (W)

An element whose symbol 'W' does not correlate to its English name.

Atom

The smallest particle of an element that can exist and still have the properties of that element; an element is composed of atoms of the same identity.

Diatomic Molecules

Elements that exist in their elemental form as two of the same atoms bonded together (e.g., H₂, O₂, N₂), representing their most stable and naturally occurring state.

Dalton's Atomic Theory (Postulate 1)

All matter is made up of small particles called atoms.

Dalton's Atomic Theory (Postulate 2)

All atoms of a given type are similar to one another and significantly different from all other types.

Dalton's Atomic Theory (Postulate 3)

The number and arrangement of different types of atoms in a pure substance determines its identity.

Dalton's Atomic Theory (Postulate 4)

A chemical change is a combination, separation, or rearrangement of atoms to form new substances.

Dalton's Atomic Theory (Postulate 5)

Only whole atoms take part or result from any kind of chemical reaction.

Subatomic Particle

A particle smaller than the atom, but which constitutes the atom's structure.

J.J. Thompson

Discovered the electron in 1897 using a cathode ray tube experiment.

Cathode Ray Tube Experiment

An experiment by J.J. Thompson that showed a beam bending towards a positive magnet, indicating the presence of negatively charged particles.

Electrons

Negatively charged subatomic particles, very lightweight, that exist outside the nucleus in a cloud-like region, each with an approximate negative one charge.

Plum Pudding Model

J.J. Thompson's proposed model of the atom as a uniform positive sphere with negatively charged electrons scattered throughout it.

Ernest Rutherford

Designed the gold foil experiment in 1911, leading to the discovery of the atomic nucleus and protons.

Alpha Particle

High-energy, positively charged particles used by Rutherford in his gold foil experiment.

Gold Foil Experiment

Rutherford's experiment where alpha particles were shot at a thin piece of gold foil, resulting in scattering, which disproved the plum pudding model.

Nucleus

A small, dense, positively charged core at the center of the atom, discovered by Rutherford, containing most of the atom's mass and its protons and neutrons.

Protons

Positively charged subatomic particles located inside the nucleus, weighing approximately one atomic mass unit, discovered by Rutherford.

Niels Bohr

Proposed the Bohr Model, which depicted electrons existing in orbits around the nucleus, similar to a solar system.

James Chadwick

Discovered the neutron, a neutral subatomic particle in the nucleus, through an experiment involving charged oil droplets.

Neutrons

Neutral subatomic particles located inside the nucleus, contributing significantly to the atom's mass (approximately one atomic mass unit), discovered by James Chadwick.

Atomic Mass Unit (AMU)

A unit used to measure the extremely small masses of subatomic particles and atoms; defined as one-twelfth of the mass of one carbon-12 atom.

Atomic Number (Z)

The number of protons in an atom's nucleus, which uniquely identifies an element. On the provided periodic table, it is the whole number above the element symbol.

Mass Number

The sum of the number of protons and neutrons in an atom's nucleus, expressed in atomic mass units; it is always a whole number without decimals.

Number of Neutrons

The calculation derived by subtracting the atomic number (number of protons) from the mass number.

Neutral Element

An element with no overall positive or negative charge, meaning the number of protons equals the number of electrons.

Isotope

Atoms of the same element (same atomic number and number of protons) that have a different number of neutrons, resulting in different mass numbers.

Isotope Notation

Designates an isotope by the element name followed by a dash and a number (e.g., Chlorine-35), where the number refers to the mass number of that specific isotope.

Atomic Weight (Weighted Isotopic Average)

The average of all the isotope masses for a particular element, taking into account the abundance of each naturally occurring isotope; it is the decimal number found on the periodic table below the element symbol.

Isotope Mass

The specific mass of a particular isotope, used in calculating the atomic weight.

Percent Abundance

The relative proportion (percentage) of each isotope present for a particular element in a natural sample.

Mass Spectrometer

An instrument used to determine the percent abundance and relative mass of each isotope for an element in a sample.

Calculating Atomic Weight

The formula involves multiplying each isotope's mass by its decimal percent abundance, then summing these products for all isotopes present.

Periodic Table (Overview)

A systematic arrangement of all known elements, each with its unique symbol, atomic number, and atomic weight, used to understand chemical trends and properties.